In Brief: Most of those accounts are about the sound of the towers as they were collapsing, and some are about cars, trucks, etc. that were on fire after the collapses. None have seen actual bombs, or claim nowadays that actual bombs went off. Accounts before the collapse are of bodies from the towers hitting the ground or other structures.

The bomb theory would require a huge risk of getting caught beforehand, starting the explosions from the wrong part of the towers, a huge amount of people who would have to remain silent, a risk of making the explosions too visible and getting caught, enormous amount of wiring. Remember, no one is claiming to have seen or heard actual bombs.

In Brief: The explosion in the north tower elevator shafts, which damaged several floors, the lobby, and basement levels, was caused by jet fuel. Why risk getting caught by blowing up the basement? What if the collapse started accidentally from there? There is no sense weakening the base, if the collapse should start from the top.

Claim: Larry Silverstein said Pull, meaning they decided to demolish the building.

The quote goes: "I remember getting a call from the, er, fire department commander, telling me that they were not sure they were gonna be able to contain the fire, and I said, 'We've had such terrible loss of life, maybe the smartest thing to do is pull it.' And they made that decision to pull and we watched the building collapse."

In Brief: 'They' made the decision to pull, which means the Fire Department made the decision. Fire Departments don't demolish buildings. Why would Larry Silverstein accidentally admit demolition on a non-live TV-show and not have it edited away. Pull meant the personnel, that had to be pulled from the scene, because WTC 7 showed critical signs of failure.

"The most important operational decision to be made that afternoon was the collapse had damaged 7 World Trade Center, which is about a 50 story building, at Vesey between West Broadway and Washington Street. It had very heavy fire on many floors and I ordered the evacuation of an area sufficient around to protect our members, so we had to give up some rescue operations that were going on at the time and back the people away far enough so that if 7 World Trade did collapse, we wouldn't lose any more people."

In Brief: There is a huge amount of eyewitness material comfirming the south side damage caused by the falling north tower debris, as well as numerous witnesses confirming the large fires. Also videos from the south side show large amount of smoke from almost each floor.

In Brief: WTC 7 damaged surrounding buildings. The Penthouse collapsed 6-7 seconds before the rest of the building. The pile was not tidy. Pictures from the scene confirm this. Those are not signs of controlled demolition.

In Brief: The colour of the material means nothing. The material flowing out the window that was glowing wasn't necessarily due to black body radiation but could have been due to spectra generated by chemical reactions in various materials in the melt that may have interacted with each other. A third factor that affects color would be reflection of ambient light, which isn't black body radiation and isn't spectra due to chemical reactions.

The elements that Professor Jones reports finding have already been discovered by other WTC dust surveys, who for the most part don’t seem surprised by their presence. It seems likely that, in all cases, there are other WTC sources that can deliver far more of these elements than you would ever see from thermite/ thermate.

There’s also no clear evidence that the suspect elements are available in proportions that match what you’d expect from a thermite/ thermate reaction.

NIST investigators and experts from the American Society of Civil Engineers (ASCE) and the Structural Engineers Association of New York (SEONY)—who inspected the WTC steel at the WTC site and the salvage yards—found no evidence that would support the melting of steel in a jet-fuel ignited fire in the towers prior to collapse.

Under certain circumstances it is conceivable for some of the steel in the wreckage to have melted after the buildings collapsed. Any molten steel in the wreckage was more likely due to the high temperature resulting from long exposure to combustion within the pile than to short exposure to fires or explosions while the buildings were standing.

In his new 2008 paper Steven Jones presents three
different spectra of spherical particles (he has found even more
spectra not mentioned in the paper). Jones' thermite/thermate theory is
effectively debunked by the great variety of spectra of iron-rich
microspheres in the WTC dust. This proves the spheres came from many
different sources. If some of these sources were present before 9/11,
e.g. in construction debris from welding and cutting operations, Jones
needs to show us how he can distinguish between such particles and
particles produced in the WTC fires.

He ignores all the natural explanations for his findings, including:

Pigments and fillers used in plastics

Fly ash from the combustion of cellulose-based materials: wood, cardboard and paper

Welding fume left in the towers from construction activities

Wear particles from grinding and cutting during construction of the towers

Iron powder cores from electronics (e.g. transformer cores)

NYC background levels of particulate from general environmental sources

Thanks to Dr. Frank Greening (Apollo20) for putting this all in plain English in this thread.

In Brief: The towers had their unique design. They can not be compared to other buildings, which have not even been damaged by an impact before the fires. The claim often includes comparisons to the Madrid Windsor fire. However, Windsor had a reinforced concrete structure with steel. All the steel parts collapsed there.

The towers were hit by airplanes traveling at very high speeds. Fireproofing was removed from the impact zones. Why would you fireproof steel if fire did nothing to it? The steel structure and supporting columns were severed and weakened by the impacts and further by the fires. Hat trusses redistributed the loads to the remaining columns, that eventually couldn't support the enormous masses of the upper parts of the buildings. The collapses started from the areas of the aircraft impact. The collapse was not improbable, it was evident.

Controlled demolition is never started from the top. And nothing was controlled in the twin towers collapse. Debris flew everywhere.

In Brief:A buildup of pressure caused by the compression of air between the floors pushed debris out of the already broken windows and/or open vents. Falling debris like elevators or elevator parts/motors and/or columns free falling down the elevator shafts and slamming into lower floors creating debris can also have similar effects. In a sense the floors are large plungers and the towers are just one big Syringe during the collapse.

The perpetrators would have known that all the cameras would film the event. Why make visual explosions?

In Brief: Neither of the towers fell at so called free fall speed. The surrounding debris fell faster than the towers itself. A huge piece of the core of the north tower can be seen standing for a while after the collapse. This can be confirmed from the collapse videos.

In Brief: WTC was not made of reinforced concrete. Towers had a steel structure with only 4 inch lightweight concrete floors. An enormous amount of energy was released in the collapse. That energy destroys everything.

In Brief: BBC really reported the collapse of the Salomon Brothers building, better known as WTC 7, some 20-30 minutes prior to its collapse. The news day was extremely busy and during live coverage things are often mixed up, before more information emerges to clarify the events. This report was most probably caused by the misinterpretation of the reports saying WTC 7 was in immediate danger of collapsing and personnel in the area had to be pulled away.

The confusion is very clearly shown by the fact, that building 7 is still standing in the background of the BBC reporter. This would be the biggest blunder ever by the conspirators, why would they need to release any statements about the collapse, let alone too early? This collapse report is an honest mistake, nothing more.

BBC has responded to this and clearly states the following:

"We didn't get told in advance that buildings were going to fall down. We didn't receive press releases or scripts in advance of events happening. In the chaos and confusion of the day, I'm quite sure we said things which turned out to be untrue or inaccurate - but at the time were based on the best information we had."